Used or scrap rubber has become a nuisance. Indeed, many landfills are loaded to capacity with billions of tires, causing both disposal and environmental concerns. In addition to tires, other rubber products, which can include such rubbers as butyl rubber and ethylene-propylene diene rubbers, add to the problem. Because these rubber products are generally not biodegradable, the problem can only be alleviated by the destruction and/or use of the used or scrap rubber.
It is known in the art to de-polymerize waste streams of rubber, such as tires, in an effort to reduce the volume of waste and obtain a useful byproduct. Likewise, rubber products can be devulcanized in an attempt to recycle the waste rubber.
In addition to these techniques, it is common in the art to grind waste streams of rubber and utilize the ground particles. Typically, the rubber is ground to a particle size of about 100 .mu.m to about 600 .mu.m. These ground particles are then typically compounded with other polymeric materials in an effort to make useful products.
It has been found, however, that the addition of such ground rubber particles results in a significant deterioration of the mechanical properties of the resulting polymeric composites. To overcome the reduction in physical properties, it is known in the art to condition the ground particles and/or polymeric materials with a coupling agent in an attempt to improve the interaction between the materials. For example, attempts have been made to coat ground rubber particles with ethylene-acrylic acid copolymer, which is believed to improve the interaction of the ground particles with polymeric materials such as linear low density polyethylene. Such composites are believed to have improved impact properties while retaining adequate processing characteristics.
Heretofore in the art, however, the use of ground rubber particles has been limited because of the expense of treating the ground rubber with coatings, such as ethylene-acrylic copolymers, or by using other treatments for the ground rubber. The low cost of the ground waste vulcanized rubber particles can be devoured by such treatments.
Therefore, there is a need for developing a composition of matter employing ground waste rubber, wherein the composition exhibits useful physical properties and good economy.